Trolley pole



Oct. 27,1925. 1,558,832

L. F. BURNHAM TROLLEY POLE F d July 1922 Fig. 1.

WITNESS ES: INVENTOR MW I Leland 'F-Burnham. &' BY

ATTORNEY Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

LELAND r. BURNHAM, or WILKINSBURG, PENNSYLVANIA, AssIeNoR To a. D.

I NUTTALL COMPANY, A CORPORATION or PENNSYLVANIA.

TROLLEY POL-E.

Application filed July 5,

To all whom it may concern:

Be it known that I, LELAND F. BURNHAM, a citizen of the United. States, and a resident of Wilkinsburgin the county of Allegheny and State of Pennsylvania, have invented a new and useful improvement in Trolley Poles, of which the following is a specification.

My invention relates to trolley poles and particularly to means for yieldingly mountin current collectors thereupon.

One object of my invention is the provision of a yielding means, or centering device, for a current collector of such form and arrangement that substantially no flexing of the said yielding member occurs under operative conditions.

A further object of my invention is to simplify and improve generally the construction of that type of trolley pole wherein the current collector has movement with respect thereto.

My invention is especially useful in connection with trackless vehicles wherein a plurality of current collectors are supported upon a single pole. In such constructions, it is desirable to provide for slight relative movement of the currrent collectors in order that irregularities in the relative positions of the conductors with which the collectors engage may be compensated for.

Heretofore, it has been proposed to support a pair of contact-carrying arms from a trolley pole by means of helical springs, one end of each of the springs being secured to the pole and the other end to the inner end of the arms. In such construction, a yielding effect is provided only through a flexing movement of the spring. This: continual flexing tends to shorten the life of the spring over what it would be if only torsional stresses were set up therein.

As shown in the accompanying drawing,

Figure 1 is a view, partially in plan and partially in section, of a portion of a trolley pole embodying my invention, and

Fig. 2 is a view thereof in side elevation.

A trolley pole 3 may be mounted upon the roof of a vehicle (not shown) in the usual manner and is provided with a head 4 to which a pair of arms 5 are pivotally con- 1922. Serial o. 572,932.

nected. The arms 5 each carry a'trolley harp 6 that supports current collectors 7 in at 8, to the pole head 4.-. Each of the arms 5 has a helical spring 9,one end of which is pivotally supported in the arm by a pin 10 and the other end of which is pivotally supported upon the pole head 4 by a pin 11. M g It will be seen that the arms 5 may move laterally with respect to each other, by reason of their pivotal mounting upon the pole head 4, and that the springs 9 will tend to center such arms at the position indicated in Fig. 1. Such movement is necessary in order that the trolley wheels 7 may follow lateral irregularities of spacing in the conductors (not shown) with which the wheels 7 co-operate.

By reason of the pivotal mounting of the springs 9 upon the pole head, at a point eccentric of the pivots 8, it will be seen that substantially no bending stresses are set up in the springs 9, upon lateral movement of the arms 5, but that the length of such springs will vary as such movements occur, as indicated by the dotted lines 14 and 15. The stresses set up in the springs will be those of tension or compression, depending upon the length of the are through which the arms 5, at any given time, move. It is well known that a helical spring is strongest in tension and compression and that flexing thereof tends to shorten its life.

Should one of the springs 9 become broken or unduly weakened, its associated arm 5 could still be made to function because of the fact that the lower ends of the arm 5 are of such length that undue lateral movement of one of the arms would be prevented by the engagement of its lower end with the lower end of the other arm, as will be apparent from Fig. 1. The vehicle could therefore operate. with some degree of effectiveness, regardless of the absence of one of the springs 9.

Although I have described a specific embodiment of my invention, it will be obvious to those skilled in the art that various modifications may be made in the details of construction and in the design and proportion of the several co-operating parts without departing from the principles herein set forth.

Various modifications in detail and arrangement may be made without departing from the spirit and scope of the invention, as defined in the accompanying claims.

I claim as my invention:

1. The combination with a trolley pole, of a pair of collector-supporting arms pivotally mounted thereupon, a helical centering spring for each of said arms, one end of each spring being connected to its associated arm at a point intermediate the ends of the arm and the other end thereof to the pole head.

2. The combination with a trolley pole, of a collector-supporting arm pivotally mounted thereupon and a helical spring connected at one of its ends to the arm and at the other of its ends pivotally connected to the trolley pole at a point above that at which the arm is connected to the pole but below its connection with the said arm.

3. The combination with a trolley pole, of a pair of collector-supporting arms pivotally mounted thereupon and a helical centering spring for each of the said arms, each spring being pivotally connected at one end to the pole and being pivotally connected at the other end thereof to an arm.

4. The combination with a trolley pole, of a collector-supporting arm pivotally carried thereby and a helical centering spring being connected at its opposite ends to the pole and to the said arm respectively, one of the said ends being pivotally supported;

5. The combination with a supporting member, of a contact-carrying arm pivotally carried thereby and a helical centering spring for the arm so connected to the said member and the arm respectively that no fiexure thereof occurs during its normal operation.

6. The combination with a'trolley pole, of a pair of collector-supporting arms pivotally mounted thereupon, and a helical centering spring for each of said arms, each of said springs having one end pivotally connected to its associated arm and its other end pivotally connected to the pole at a point above that at which said arm is pivotally mounted.

In testimony whereof, I have hereunto subscribed my name this 26th day of June 1922.

LELAND F. BURNHAM. 

